Although vaccines and toxoids (diphtheria and tetanus) are considered to be compatible with breastfeeding, their use should be limited to those situations where there is a clinical risk of maternal exposure to the infecting organism. This includes risks due to domestic, occupational and travel exposure.
It is considered that there is no risk to breastfed infants after administration of inactivated vaccines and toxoids (diphtheria/tetanus). Live, attenuated vaccines are not considered to pose a risk to the infant except yellow fever vaccine.
Breastfeeding can enhance the response of young infants to certain vaccine antigens
Some vaccines contain thiomersal as a preservative. However, the small amount of mercury present is not considered to present a risk to a breastfed infant.
Vaccines used only in childhood have been omitted. The infant should still receive all vaccines (or vaccine components) used in childhood immunisation programmes even if the mother receives the vaccine separately.
In the UK, advice on the use of vaccines, including breastfeeding, is published in Immunisation against infectious disease: the green book